The invention relates to a fan system and a method for controlling a fan motor.
The invention relates to a fan system for the regulated cooling of an internal combustion engine of a motor vehicle. In the invention relates further to a method for controlling a fan motor.
Fan motors in engine cooling fans are normally triggered almost continuously variably by high-frequency cycle regulators (so-called FCMs or fan control modules). Among other things, this makes it possible to coordinate the fan power with the actual cooling demand. The cycle regulator itself is normally triggered with the aid of a low-frequency pulse-width modulation signal in the range of approx. 5 to 300 Hz, which specifies the degree of triggering for the fan motor.
A fan system for conducting regulated cooling for an internal combustion engine in a motor vehicle is designed for a cooling air demand at very high ambient temperatures and high cooling demand of the internal combustion engine. Normally, a fan motor for this type of fan system features power in the range of 300 to 600 W. The cycle regulators are designed correspondingly and are used to trigger the fan motors in a suitable manner so that the desired cooling power is provided.
The fan motor is normally triggered with frequencies above 18 kHz.
Although, as a rule, fan motors must be designed for high maximum required cooling power in order to be able to make the required cooling power available under extreme operating conditions, the fan motors are charged only with a clearly lower power and therefore with a lower current for a majority of the overall operating time in normal operation.
As a rule, a fan motor has a commutator via which the rotor coils of the fan motor can be energized with the aid of contact brushes. In the case of long-lasting triggering by current that is too low and with a fan motor rpm that is too low, the commutator normally “gets pasty,” i.e., carbon dust, dirt, oil, etc. gets deposited in the slots between the commutator's contact lamellae, whereby the pastiness from the carbon dust is frequently conductive and therefore causes a short circuit or reduced resistance between the lamellae.